| Abstract: | Immigration is an important factor in America's population growth. In the last 200 years over 50 million persons immigrated to the U.S.; 99.6% of the current total population are descendents of those immigrants. In the 1930s, American population decreased by about 7.2/1000, but during the 1950s the annual rate of natural increase rose to 18.5/1000. In the 1960s, this rate began to decrease until the 1970s when it was about 9/1000. By 1981 and 1982, the rate of natural increase declined to 7/1000. These changes are due to the relatively slow decline in the mortality rate of the last 30 years (10.6/1000 in 1945 to 9/1000 in 1981) and to the fluctuations in birth rates (from 19.5/1000 in 1945 to a high of 25.3/1000 in 1957 and back to 16/1000 in 1981). Birth rates are influenced by factors such as the number of fertile women, age structure, fecundity, marriage, family, occupation, and education. In 1950 there were 38,920,000 women aged 15-49, and by 1980 there were 57,630,000. Of these, in 1950, 31.28% were aged 20-29, the most fertile period for women, as compared with 35.04% in 1980. Thus, in postwar America, the changes in birth rate did not follow changes in the number of fertile women. Marriage patterns also underwent changes, particularly in the last 20 years. From 1930 to 1935, the marriage rate was 8.6/1000. By 1945, it rose to 16.4/1000. But during the 1960s, an increasing number of women aged 20-29 years remained unmarried. At the end of the 1970s, there was also an increase in the number of married women who did not have children. Furthermore, the number of divorces increased, an additional reason for a declining birth rate. Changes in family structure also influenced postwar American reproduction. In the last two decades, the traditional family has almost disappeared and the nuclear fammily is on the decline. By 1970 there were more people living alone, single parent families, and unrelated people sharing a domicile, than there were family units. Also, educated women who worked often married at a later age, thus placing restrictions on the birth rate. |
